During the drilling of wells the above-ground well equipment is assembled in a certain sequence to provide support and a safe pressure seal for strings of casing and/or tubing that are lowered downwardly into the earth. In a typical well installation, a drive pipe is initially installed at the desired well location, followed by a conductor, large diameter (surface) casing, protective casing, and production casing. The weight of the large diameter casing is typically supported by use of a large diameter casing hanger, (FIG. 1), supported within a bowl that makes up a lower portion of the well assembly.
Once the large diameter casing is set, a diverter assembly used for well flow control is removed from the bowl. Another bowl is installed on top of the large diameter casing bowl. The diverter assembly is then reinstalled on top of the new bowl and then the drilling process is repeated to allow a small diameter (protective) casing to be lowered downwardly within the hole.
During the period when the diverter assembly is removed from the large diameter casing hanger bowl, the personnel and equipment associated with the well assembly process are exposed to a greater risk of an uncontrolled well blowout than when the diverter assembly is installed on the large diameter casing hanger bowl.
From an economic standpoint, disconnection of the diverter assembly from the large diameter casing hanger bowl and its subsequent reconnection requires time and effort that could be better directed to the installation of the casing and tubing within the well.
A method and apparatus therefore need be developed that eliminates the unnecessary disassembly of the diverter assembly, with its subsequent reinstallation upon the well as it is being assembled. Such a method and apparatus would decrease the assembly costs of each well, as well as increase the safety of the personnel and equipment associated with the well installation.